The use of chlorine to sanitize freshly harvested produce (e.g., fruits and vegetables) has been well-described. Generally, chlorine is added to water as a gas to produce hypochlorite which is the active sanitizing agent. A use level of about 10 ppm and 100 ppm has been previously described as being effective for reducing microbial load and being effective against pathogens. However, while chlorine can be an effective sanitizing agent, chlorine alone has not been shown to be a completely effective kill step (i.e., a point in produce processing where potentially deadly pathogens are eradicated from the product, usually by killing the pathogen). Moreover, no single sanitizing agent has been shown to be a highly effective kill step.
The identification of a kill step in the sanitizing of fresh cut produce has remained elusive. Numerous methodologies have been described that claim additional microbial kill when compared to chlorine alone. In general, they either present additional problems or are not as effective as chlorine alone. While many of the contaminant microbes are non-pathogenic to humans and only represent a challenge to shelf-life, the fact that these products are grown in open fields presents a risk of exposure to soil- and air-borne food pathogens from Salmonella, E. coli, and Listeria species. Their ubiquitous distribution in nature must be addressed and eliminated. However, their elimination is further complicated by the fact that these pathogens and other non-pathogenic bacteria quickly form biofilms which provide additional protection from water-based sanitizers. The removal of these biofilms makes leaf-borne bacteria more susceptible to attack and destruction by added sanitizers.
Therefore, there is a need to develop a method of utilizing multiple sanitizers with various modes of attack that provide a multiple hurdle approach to sanitizing that provides a more effective reduction in microbial load than chlorine alone, reduces or eliminates human pathogen contamination, and increases produce shelf-life.